When a fart (guff) is caught in the hand and then released into somebody's mouth as a tasty treat.

Mum: "I wish I'd ordered some dessert at the restaurant, i'm still hungry!"
Son: "Don't worry Mum, you can eat this if you like..."
--- Son farts in hand and forces it into his mother's mouth---
Son: "Guff Cake!"
Mum: "Thank you son, I feel much better now"
Son: "That's ok Mum, anytime."